Epidemic Investigation of Diphtheria, Republic of Kazakhstan, 1990–1996

The diphtheria epidemic that began in Russia in 1990 reached Kazakhstan in 1992 when 45 case-patients (a 50% increase over 1991) were reported. In 1993, 82 case-patients were reported, and 489 were reported in 1994. The epidemic peaked in 1995 when 1105 case-patients were reported (incidence rate=6.7/100,000 population). In 1996, after public health practice modifications and several mass vaccinations, 455 case-patients were reported. From 1990 to 1996, children </=14 years old represented 35% (2234) of the reported case-patients (and 33% of the population) but had a disproportionate share (49%) of the fatalities. Females represented 63% of the adult case-patients. In 1996, 297 (65%) of 455 case-patients and 26 (84%) of 31 fatalities were unvaccinated. Kazakhstan controlled the diphtheria epidemic by using a multifaceted public health strategy of prevention and control, which included changing the routine immunization schedule, modifying the official list of contraindications to vaccination, conducting mass campaigns to vaccinate persons, and treating close contacts of case-patients with antibiotics.